I have written this blog about Australian circulating coins but the principle applies to other countries and currencies.
The Australian circulating coins are minted by The Royal Australia Mint (RAM) and are the coins you will find in your change. They are the coins (cash) used to buy and sell goods in the normal course of commerce.
The Perth Mint and occasionally other mints have minted coins for the Commonwealth of Australia during times of increased demand. Also the gold sovereigns were minted by various mints operating in Australia at the time.
In 1966 the Australian currency system changed to a decimal system replacing the Imperial coinage that was first issued in 1911 the foundation of the Commonwealth of Australia
The original 1966 decimal coins comprised 1c 2c 5c 10c 20c and a round 50c silver piece.. In 1969 the shape and composition of the 50c changed to Cupro Nikel and the current multi sided coin remains to this day.
The standard circulating coins depict Australian animals with the 50c displaying the Australian Coat of Arms.
When the $2 coin was introduced it carried a portrait of an Aboriginal elder.
In 1984 the $1 was introduced and the 1c and 2c dropped and the $2 introduced in 1988.
The circulating coins can be collected in original Bank rolls or Mint Rolls where 20 or 25 coins are rolled in paper.
A favorite method of collecting is also to store coins in albums. The most popular albums for storing coins are the Lighthouse and Dansco albums.